Atto-Scale Noise Near-Infrared Organic Photodetectors Enabled by Controlling Interfacial Energetic Offset through Enhanced Anchoring Ability

Abstract

The near-infrared (NIR) sensor technology is crucial for various applications such as autonomous driving and biometric tracking. Silicon photodetectors (SiPDs) are widely used in NIR applications; however, their scalability is limited by their crystalline properties. Organic photodetectors (OPDs) have attracted attention for NIR applications owing to their scalability, low-temperature processing, and notably low dark current density (JD), which is similar to that of SiPDs. However, the still high JD (at NIR band) and few measurements of noise equivalent powers (NEPs) pose challenges for accurate performance comparisons. This study addresses these issues by quantitatively characterizing the performance matrix and JD generation mechanism using electron-blocking layers (EBLs) in OPDs. The energy offset at an EBL/photosensitive layer interface determines the thermal activation energy and directly affects J(D). A newly synthesized EBL (3PAFBr) substantially enhances the interfacial energy barrier by forming a homogeneous contact owing to the improved anchoring ability of 3PAFBr. As a result, the OPD with 3PAFBr yields a noise current of 852 aA (J(D) = 12.3 fA cm(-2) at V -> -0.1 V) and several femtowatt-scale NEPs. As far as it is known, this is an ultralow of J(D) in NIR OPDs. This emphasizes the necessity for quantitative performance characterization.